1.1 Field of the Invention
In inventory-intensive wholesale and retail operations, bar coding systems have become popularly employed in tracking the flow of products. Bar coding systems frequently include not only printing and reading equipment, but also means for verification. Verification is a process by which a bar code label is analyzed to determine if it has been printed in accordance with print specifications dictated by the particular bar code symbology (e.g., UPC, Code 39, MSI/Plessey, etc.) and industry group (e.g., ANSI, LOGMARS, IATA, etc.) against which it was printed.
The present invention relates generally to optical scanning systems for use in bar coding systems. More particularly, the present invention relates to portable, non-contact bar code verifier arrangements and method by which the quality and readability of scanned bar code labels are measured, analyzed, and reported in a convenient and inexpensive way.
1.2 Description of Prior Art
The advantages of bar coding systems are well-known. In order for a bar code system to effectively handle inventory information, it must comprise at least two properly functioning subsystems: a bar code printing system and a bar code reading system. It is the shortcomings in either or both of these two subsystems that often necessitate a third, a bar code verification system.
Among the problems occurring as a result of faulty printing systems are insufficient contrast between bars and spaces (collectively referred to in the art as "elements") of a bar code label, unintentional bar width growth or loss due to ink spread or shrinkage, ink voids or specs or other printing errors. Bar code reading systems fail due to hardware problems such as maladjusted or ineffective sensors, emitters, or processors in reading apparatus, and, in addition, due to user mistakes such as improper positioning of the scanner relative to the bar code label of interest or improper programming of the processor in the reading apparatus.
For these reasons, those who employ bar code systems often have need for a verification system which will effectively identify existing or potential problems in the printing and reading systems, thus allowing the user to adjust the bar code system to derive its maximum efficiency and performance potential. For example, bar code printers might use a verification program as part of a quality control scheme designed to monitor print quality trends during the printing process and stop printing as bar codes begin to be printed out of specification. Alternatively, downstream bar code system users, warehouse inventory managers, for example, might use information derived from a bar code verifier to alert him/her to the need to print new labels for a group of products, or to note bar code labels that will require special handling as they move through the system. An article by one of the present inventors on the subject of bar code verification is instructive in pointing out potential bar code problems, and potential verification solutions. See "Opinion" by Tina Barkan at: "Automatic I.D. News," November 1988.
Previously, two types of verifiers, both requiring contact of the scanner with the bar code label, have been employed. The first, a contact-wand, uses a light emitting source at the end of a pencil-looking wand which is guided manually over the bar code label by the user. Light emitted from the light source is reflected by the bar code label pattern and received by a detector also in the wand. This type of verifier requires a single pass of the wand over the bar code label to check the label and acquire the appropriate information. A second type of prior art verifier is the laser-based verifier which also requires contact between the head of the scanner unit and the bar code label. However, the laser-based verifier checks the bar code label multiple times as the laser beam sweeps rapidly back and forth across the label.
The known optical scanning verifier systems have not proven to be altogether satisfactory for a variety of reasons. First, contact-type verifiers are inconvenient. Furthermore, by virtue of the fact that they am designed to block out ambient lighting conditions, contact-type verifiers are not accurately predictive of bar code readability under various reading conditions affecting noncontact-type readers. Second, analysis of quality and readability of bar code labels in prior art verifiers has not been as descriptive and instructive as often desired. Third, prior art verifiers have not had the added capability of being usable as bar code readers. Fourth, prior-an laser-based verifiers have generally not been conveniently portable due to their large size. Fifth, prior-art verifiers have been expensive due to their large number of components required for signal processing. Finally, due to the use of separate technology for verification and reading, bar code verifiers have not been accurately predictive of a reader's ability to read a particular bar code label.